A 28-year-old nulliparous woman from Bangalore presents with a 3-month history of prolonged menstrual bleeding (10–12 days per cycle), with normal cycle intervals of 28 days. She reports no dysmenorrhea, pelvic pain, or intermenstrual spotting. On examination, the uterus is normal in size and consistency, and the cervix is clear. Pelvic ultrasound is entirely normal, with endometrial thickness of 8 mm in the follicular phase. Hemoglobin is 10.5 g/dL. Coagulation profile (PT, aPTT, platelet count) is normal. What is the most likely diagnosis?

Explanation

## Clinical Diagnosis: Idiopathic Menorrhagia (Ovulatory Abnormal Uterine Bleeding) ### Key Clinical Features **Key Point:** Regular cycle intervals (28 days) with prolonged duration (10–12 days) in the absence of structural abnormality, coagulopathy, or systemic disease defines **idiopathic menorrhagia** — a diagnosis of exclusion in ovulatory women. This patient has: - **Regular ovulatory cycles** (28-day interval suggests normal luteal phase) - **Prolonged menstruation** (heavy flow lasting >7 days) - **Normal pelvic examination** (normal uterine size, no masses) - **Normal ultrasound** (no fibroids, polyps, adenomyosis; normal endometrial thickness) - **Normal coagulation studies** (PT, aPTT, platelets all normal) - **No dysmenorrhea or pelvic pain** (argues against adenomyosis) - **Nulliparous status** (relevant for management decisions) ### Pathophysiology of Idiopathic Menorrhagia 1. **Abnormal local endometrial hemostasis** — impaired platelet aggregation, reduced fibrinolytic inhibitors (increased tissue plasminogen activator) 2. **Abnormal prostaglandin metabolism** — elevated endometrial PGE~2~ and PGF~2α~, leading to increased vasodilation and bleeding 3. **Abnormal angiogenesis** — increased vessel density and abnormal vascular architecture 4. **Normal ovulation** — distinguishes from anovulatory dysfunctional uterine bleeding ### Differential Diagnosis Table | Feature | Idiopathic Menorrhagia | Dysfunctional (Anovulatory) | Von Willebrand Disease | Endometrial Hyperplasia | |---------|------------------------|----------------------------|------------------------|------------------------| | **Cycle regularity** | Regular (ovulatory) | Irregular, unpredictable | Variable (may be regular) | Irregular | | **Duration of bleeding** | Prolonged (>7 days) | Prolonged, variable | Prolonged, often severe | Prolonged | | **Pelvic ultrasound** | Normal | Normal | Normal | Endometrial thickening (>12 mm) | | **Coagulation studies** | Normal | Normal | **Abnormal** (↓ vWF, ↓ Factor VIII) | Normal | | **Age group** | Reproductive (any age) | Adolescent or perimenopausal | Any age (family history) | Perimenopausal, obese | | **Dysmenorrhea** | Absent | Absent | Absent | Absent | | **Diagnosis** | Exclusion diagnosis | Exclusion diagnosis | Blood test (vWF:Ag, Factor VIII) | Endometrial biopsy | ### High-Yield Points **High-Yield:** Idiopathic menorrhagia is the **most common cause of abnormal uterine bleeding in ovulatory women** (40–50% of menorrhagia cases). It is a **diagnosis of exclusion** — structural, coagulation, and systemic causes must be ruled out first. **Mnemonic — PALM-COEIN (AUB classification):** - **P**olypoid lesions - **A**denomyosis - **L**eiomyoma (fibroid) - **M**alignancy - **C**oagulopathy - **O**vulatory dysfunction - **E**ndometrial (idiopathic menorrhagia) - **I**atrogenic - **N**ot yet classified This patient fits **E** (Endometrial — idiopathic menorrhagia) after exclusion of P, A, L, M, C, O, I. ### Management Approach ```mermaid flowchart TD A["Abnormal Uterine Bleeding<br/>Regular cycles, prolonged duration"]:::outcome --> B{"Structural abnormality<br/>on ultrasound?"}:::decision B -->|Yes| C["Manage structural lesion<br/>fibroid, polyp, adenomyosis"]:::action B -->|No| D{"Coagulation disorder<br/>suspected?"}:::decision D -->|Yes| E["Check PT, aPTT, platelets<br/>vWF:Ag, Factor VIII"]:::action D -->|No| F{"Systemic disease<br/>or medication?"}:::decision F -->|Yes| G["Manage underlying cause"]:::action F -->|No| H["Idiopathic Menorrhagia<br/>Diagnosis of Exclusion"]:::outcome E -->|Abnormal| I["Treat coagulopathy"]:::action E -->|Normal| H G --> H ``` ### First-Line Treatment - **NSAIDs** (mefenamic acid 500 mg TDS during menses) — reduces bleeding by 20–50% - **Tranexamic acid** (1 g TDS during menses) — reduces bleeding by 40–60%, most effective - **Levonorgestrel-releasing IUD (Mirena)** — reduces bleeding by 90%, excellent for nulliparous women - **Combined oral contraceptives** — regulate cycle, reduce flow **Clinical Pearl:** Tranexamic acid is contraindicated in women with thrombophilia or thrombotic disease; NSAIDs are first-line in such cases. [cite:Jeffcoate's Principles of Gynaecology 8e Ch 11; FIGO Classification of Abnormal Uterine Bleeding]